Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B37/00—Lapping machines or devices; Accessories
  • B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
  • B24B37/07—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool
  • B24B37/10—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for single side lapping
  • B24B37/105—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for single side lapping the workpieces or work carriers being actively moved by a drive, e.g. in a combined rotary and translatory movement
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
  • B24B49/16—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation taking regard of the load
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
  • H01L21/30625—With simultaneous mechanical treatment, e.g. mechanico-chemical polishing

Definitions

• the present invention relates generally to method and apparatus for fabricating semiconductor devices, more particularly to method and apparatus for chemically mechanically polishing semiconductor substrates with enhanced durability, reliability and polishing effectiveness.
• the metal interconnection layers or inter-layers for insulating the metal interconnection layers should be planarized to secure a focus margin for a following photolithography process.
• the insulating inter-layers have been planarized using a BPSG (borophsophosilicate glass) reflow technique.
• BPSG borophsophosilicate glass
• a deposited BPSG layer is planarized by flowing the BPSG layer while heating the substrate to ⁇ OO.degree. C. or more.
• the temperature of the reflow process is too high to be applicable to aluminum interconnection layers.
• the reflow technique is inadequate for the planarization of sub-micron fine patterns or the global planarization of a substrate.
• a resist etchback technique is known in the art of surface planarization.
• the resist etchback technique however has several drawbacks such as the increase in the thickness of insulating inter-layers, the necessity of additional processes and the difficulty of controlling etch ratio of insulating inter-layers and resist layers.
• CMP chemical mechanical polishing
• the slurry contains a mechanical polishing agent, such as alumina or silica.
• the slurry contains de-ionized water and selected chemicals which etch various surfaces of the substrate during processing.
• the chemicals include pH controlling solution, such as KOH or NaOH.
• the mechanical polishing and chemical polishing are simultaneously performed during overall polishing process.
• the polishing rate is proportional to the parameters such as the pressure of the polishing pad on the substrate, and the relative velocity between the substrate and the polishing pad.
• the perimeter of the substrate tends to rotate at higher velocity than the center of the substrate. Therefore, in the CMP process used for semiconductor device fabrication, the relative velocity between the substrate and the polishing pad is maintained to be equal by combining two rotational movements with same rotational velocities.
• FIG. 1 is a partial sectional view of a CMP apparatus in which the conventional CMP process is employed.
• a platen drive motor 130 rotates a polishing pad 110 attached to a platen 120.
• a substrate 140 retained in a substrate carrier 150 is rotated against the pad 110 by a carrier drive motor 160.
• the substrate 140 and the pad 110 rotate with a slurry supplied to the interface of the substrate 140 and the pad 110, the substrate 110 is chemically and mechanically
• the moving velocity v p ⁇ pa ⁇ of the substrate relative to the polishing pad can be represented by equation 1, that is, a difference between substrate moving velocity VPH and pad moving velocity v?e .
• equation 1 can be expressed as following equation 2.
• ⁇ H is the rotational angular velocity of the substrate
• ⁇ p is the rotational angular velocity of the polishing pad
• ⁇ rH is the position vector from the substrate rotation center to the point P
• ⁇ r? is the position vector from the polishing pad rotation center to the point P
• rcc is the position vector from the polishing pad rotation center to the substrate rotation center.
• Vp i p d - ⁇ p " rcc (equation 3 )
• the relative moving speed between the substrate and the polishing pad depends upon the rotational angular velocity and the distance between two rotation centers, but not the position or direction on the substrate.
• the substrate can be uniformly polished since the relative moving speed between the substrate and the polishing pad is equal at all points on the substrate.
• FIG. 3A shows sequentially the states that the substrate and the polishing pad are rotated by 0, 45, 90, 180 and 270 degrees, respectively. Black dots are inserted in the figure to indicate the absolute positions of the substrates and the polishing pad.
• FIG. 3 A can be expressed by FIG. 3B.
• FIG. 3C all points of the substrate trace a circular path with a radius of r cc on the polishing pad.
• any trivial non- uniformity on the polishing pad can exert a harmful effect upon the substrate. Therefore, the area which a point of a substrate traces should be widened. For this reason, it is desirable that a substrate carrier or a platen is reciprocated within a predetermined range with a relatively low speed, as a sub motion.
• the movement which induces chemical-mechanical polishing effect will be referred to as "main motion”
• the movement, making little contribution to the polishing, for obtaining other effects will be referred as "sub motion”.
• the rotational motions of the substrate and the polishing pad are examples of the main motion.
• FIG. 4A shows sequentially the states that the substrate and the polishing pad are rotated by 0, 45, 90, 180 and 270 degrees, respectively, in case of combining uniform- velocity rotational motions of the substrate and the polishing pad with their low speed reciprocating motions, as sub motions.
• FIG. 4A can be expressed by FIG. 4B.
• the area which an arbitrary point of a substrate traces is widened as shown in FIG. 4C.
• all points of the substrate trace the same area and the tracing paths are uniformly spread in all directions of the polishing pad.
• the ratio of the period of rotation movement to that of reciprocating movement is not a simple integer. If the ratio is a simple integer, the points of the substrate trace a closed curve path within the donut shape of FIG.
• 5,554,064 discloses a CMP method that combines a non- rotational orbiting of a polishing pad (main motion) with a low speed rotation of a substrate (sub motion).
• U.S. Pat. No. 5,582,534 discloses methods and apparatus for CMP that combines a rotation of a polishing pad (main motion) with an orbiting of a substrate (sub motion).
• those areas of the substrate which are located further from the rotation center experience greater cumulative movement, and therefore greater material removal, than areas of the substrate maintained closer to the rotation center.
• polishing process can be performed with only one drive means while maintaining the relative moving velocity between the substrate and pad equal for all points on the substrate.
• a second orbital movement is used as a sub motion for preventing trivial non-uniformity on the pad from exerting a harmful effect upon the substrate.
• the relative moving velocity between the substrate and pad for all points of the substrate is equal at any moments since all points of the substrate and pad move with same direction and velocity at any moments.
• FIG. 1 is a partial sectional view of a CMP apparatus in which the conventional CMP process is employed
• FIG. 2 conceptually depicts the basic conditions for uniform polishing in the prior art CMP method
• FIG. 3A to 3C are schematic views showing a prior art CMP method where the rotation velocities of the substrate and pad are equal;
• FIG. 4A to 4C are schematic views showing a prior art CMP method where the relatively low speed reciprocating movement is employed as a sub motion
• FIG. 5 A to 5C are schematic views showing the CMP method of the present invention.
• FIG. 6A and 6B are schematic views showing the effect of orbit radius exerted on the pad in the CMP method of the present invention.
• FIG. 7 is a cross sectional view of the CMP apparatus according to the embodiment of the present invention.
• FIG. 8 is a cross sectional view illustrating the configuration of the platen of the CMP apparatus of the invention.
• FIG. 9 A and 9B show the structure of the platen;
• FIG. 10A and 10B show the structure of the platen support
• FIG. 11 illustrates vacuum loading mechanism of the substrate
• FIG. 12 shows an example of measuring the pressure, imposed by the frictional force between the substrate and pad, transferred to the shaft of an orbital movement
• FIG. 5 A shows the movements of the substrate relative to the stationary pad.
• FIG. 5C shows the area which an arbitrary point of a substrate traces.
• all points of the substrate trace the same area and the tracing paths are uniformly spread in all directions of the pad.
• the ratio of the periods of two orbital movements is not a simple integer. If the ratio is a simple integer, the points of the substrate trace a closed curve path within the donut shape of FIG. 5C. Most ideally, if the ratio is not an integer but an irrational number, their tracing paths will completely cover the inside of the donut shape.
• the orbit radii and angular velocities of the substrate and pad are equal, polishing does not occur since there is no relative motion between the substrate and pad. If the orbit radii are equal and only different angular velocities contribute to the polishing of the substrate, the area which a point of a substrate traces does not increase. Accordingly, it is desirable that the orbit radii of the substrate and pad differ from each other. If the orbit radii of the substrate and pad differ from each other, all points of the substrate cover same tracing area on the pad with the tracing path uniformly spread in all directions.
• the CMP method of the present invention may employ any from the two mechanisms. If the carrier retaining a substrate weighs less than the platen, the former mechanism is mechanically more stable than the latter one.
• the present invention will be described with reference to only the former mechanism, the description however is not meant to be construed in a limiting sense. That is, the method of the present invention can be realized in accordance with the latter mechanism where the platen with a polishing pad fixed thereon moves in a main motion.
• the substrate and pad can be orbited by only one drive means.
• the CMP apparatus of the present invention further comprises decelerating means for reducing the orbital velocity of the platen.
• the substrate and pad can be orbited by only one drive means, two orbiting directions are the same.
• the substrate carrier and the platen are driven by separate driving means, they can orbit in opposite directions, which increases the relative velocity between the substrate and pad. Therefore, the maximum polishing rate can be doubled at an equal orbiting velocity, or minimum orbiting speed required for obtaining the same polishing rate can be reduced by half.
• the CMP method of the present invention may utilize two slurry-feed mechanisms.
• the slurry can be supplied to a polishing pad through a slurry port which directly drips the slurry onto the polishing pad.
• the first mechanism is utilized when the orbit radii are sufficiently large compared to the size of the substrate, more particularly when the addition of main motion orbit radius r M and sub motion orbit radius r s is equal to or larger than the radius r w of the substrate.
• the first mechanism has a drawback that it requires a larger platen compared to that used in the following second mechanism.
• the slurry is supplied to the polishing pad after passing through the polishing pad.
• the second mechanism is utilized when the orbit radii are small compared to the size of the substrate, more particularly when the addition of main motion orbit radius and sub motion orbit radius is smaller than the radius of the substrate.
• the size of the platen can be reduced.
• some portion of the pad can not be conditioned during polishing since the portion always contacts with the substrate as shown in FIG. 6B.
• the slurry can not be supplied to the portion by the method of dripping directly the slurry onto the pad.
• the problem involved in the second mechanism can be solved by supplying the slurry coming from the supply port of the platen to the contacting interface of the substrate and pad after passing through holes or slots of the polishing pad.
• the slurry feed lines connected to the platen does not twist since the orbiting platen does not rotate.
• the slurry is supplied to the polishing pad after passing through the polishing pad.
• the substrate is transferred with its polishing surface attached to the transfer member, but this method tends to damage the patterned front surface of the substrate, resulting in lowering the yield of the semiconductor devices. Therefore, it is more stable to employ the method of transferring the wafer with its backside attached to the transfer member.
• the procedure may be as following steps: (1) placing the substrate on the polishing pad while holding the backside of the substrate, (2) fixing the substrate with a substrate carrier, (3) polishing the front surface of the substrate, (4) releasing the substrate from the substrate carrier, and (5) lifting the polished substrate to transfer to another position.
• steps (1) and (2) it is desirable that the substrate is fixed to the pad to prevent the substrate from moving.
• the substrate may be fixed on the pad by a vacuum connected to the platen. The vacuum lines connected to the platen does not twist since the orbiting platen does not rotate.
• the CMP apparatus can detect the frictional force between the substrate and pad by measuring a pressure at the shaft which supports the platen.
• FIG. 7 is a cross sectional view of the CMP apparatus according to the embodiment of the present invention.
• a head holder 310 can be rotated by a rotating motor 330.
• a substrate carrier 320 orbiting about the rotation center H, spaced apart from the rotation center H of the head holder 310, is connected to the head holder 310 by bearings (not shown).
• a platen 340 with a polishing pad attached thereon is rotated by a platen drive motor 350.
• a platen base 360 is connected to a frame by a platen guide 390 to enable a predetermined range of reciprocating motion.
• An up/down drive cylinder is disposed at the central portion under the platen base 360 and a plurality of clamp cylinders 380 , under the platen 340, is provided to adjust the position of the platen 340.
• a decelerating means for providing a friction between the substrate and pad may be added around the position of the platen drive motor 350.
• FIG. 8 is a cross sectional view illustrating the configuration of the platen of the CMP apparatus of the invention.
• a rotating body 602 rotates about a center R by the platen drive motor.
• Rotating body bearings (not shown) are attached to the rotating body 602, where the central shaft B of the bearings is spaced apart from the rotating body R.
• a platen center shaft 604 is inserted in the rotating body bearings to enable the orbiting of the platen 340 with the rotation of the rotating body 602.
• a platen center shaft 604 is directly connected and fixed to a movable base 608, and the movable base 608 is fixed to an X-Y guide 610. Accordingly, the movable base 608 orbits together with the bearing center shaft B, but not rotates.
• FIG. 9A and 9B show the structure of the platen.
• FIG. 9 A is a plan view of the platen where the centers of both the slurry supply hole h and slurry channel c do not coincide with each other.
• FIG. 9B is a side sectional view of the platen. Referring to FIG. 9B, the slurry supply hole h is connected with the slurry channel c.
• FIG. 10A and 10B show the structure of the platen support.
• FIG. 10A is a plan view of the platen support. Referring to FIG. 10A , the slurry supply areas are divided into two portions O and P. The O portion shows the central channel 632 of FIG. 8, and the P portions show the peripheral channels 630 and 634, respectively.
• FIG. 10B is a side sectional view of the platen support.
• FIG. 11 illustrates vacuum loading mechanism of the substrate.
• the substrate orbit radius is smaller than the pad orbit radius
• the substrate 540 moves on the pad 614 as shown in the figure. Accordingly, there exists a portion always covered by a substrate during the polishing. If the O portion of FIG. 10A is located within the covered portion, the O portion will be located within the substrate when the substrate 540 is loaded on the pad 614. If the vaccum mechanism operates after the loading of the substrate, the substrate can be fixed on the pad even when the platen rises up.
• FIG. 12 shows an example of measuring the pressure, imposed by the frictional force between the substrate and pad, transferred to the shaft of an orbital movement.
• the shaft for supporting the platen is divided in two parts: a lower shaft portion 910 and an upper shaft portion 920.
• the adjoining section of both shaft portions is a square, and there exists a spacing between both shaft portions for the respective faces of the square.
• Four pressure sensors 930 are disposed within the spacing, and pushing plates 940 is provided with the respective pressure sensors 930 to enhance the detection performance.
• the respective pushing plates 940 press the respective pressure sensors 930 against the upper shaft portion 920.
• the frictional force between the substrate 540 and the pad 614 imposes forces, for example Fl or F2, on the platen in a tangential direction of the substrate orbit movement.
• the forces are transferred to the lower shaft portion 910 through the upper shaft portion 920.
• the pressure sensors 930 detect the pressure due to the transferred forces and generate signals according to the pressure. Accordingly, the frictional forces changing as the polishing process proceeds can directly be detected and analyzed by an additional signal processing apparatus. This helps monitor the polishing procedure and helps determine polishing-stop timing.
• uniform polishing across the substrate is guaranteed in principle in spite of using fewer number of drive means compared with the prior art.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Weting (AREA)
• Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)

Priority Applications (5)

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Cited By (2)

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Citations (4)

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• 1999
  • 1999-07-28 KR KR10-1999-0030803A patent/KR100443330B1/ko not_active Expired - Fee Related
  • 1999-07-31 EP EP99935149A patent/EP1031166B1/en not_active Expired - Lifetime
  • 1999-07-31 JP JP2000562942A patent/JP2002521839A/ja not_active Ceased
  • 1999-07-31 AT AT99935149T patent/ATE308116T1/de not_active IP Right Cessation
  • 1999-07-31 WO PCT/KR1999/000419 patent/WO2000007230A1/en not_active Ceased
  • 1999-07-31 US US09/509,334 patent/US6315641B1/en not_active Expired - Lifetime
  • 1999-07-31 DE DE69927935T patent/DE69927935T2/de not_active Expired - Fee Related

Patent Citations (4)

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